"Families often, and friends, have kept firearms in cupboards and other places, they haven't been in locked storage and they are at risk of being stolen and we know that criminals will source them from wherever," he said.

A total of 1,242 firearms were given up, with more than 700 of those coming from the Perth metropolitan area.

It followed an amnesty in WA four years ago which saw 1,281 weapons surrendered.

Police Minister Michelle Roberts said she was pleased with the response.

"The amnesty has actually exceeded our expectations," she said.

"It was a national effort, all states involved over that period of three months, so there's national media on it, that may have had an impact in getting the message out a little more widely."

Commissioner Dawson said there was still an opportunity for anyone who missed the formal time frame.

"For those that for whatever reason have not handed in any firearms and you're not the lawful licensed owner then still contact police," he said.